Variable stroke multiple pump

ABSTRACT

The pump comprises two cylinders with pistons actuated from a common shaft fitted with eccentrics corresponding to each piston, between each eccentric and the large end of each connecting rod being interposed a disc with an opening which receives said eccentric, said opening being offcentered with respect to said disc so that by rotating said disc with respect to said eccentric the crank radius of the connecting rod and consequently the stroke of the corresponding piston can be varied at will.

9. 1 P. United States atent 1191 1111 3,738,230 Censi 1 June 12, 1973[54] VARIABLE STROKE MULTIPLE PUMP 1,640,509 8/1927 Lowe 92/133 X2,929,334 3/1960 Panhard 92/13 X [761 Invent Gmrg Censi, (5611001982,935,112 5/1960 Vangerpen 92/13 x Rome, Italy 3,171,287 3/1965 Jesse92/13.? x 3,180,178 4/1965 Brown et a1. 92/13.? X [22] 1971 3,257,9536/1966 Pinkerton 92/137 x [21] Appl. No.: 120,282

Primary Examiner-lrwin C. Cohen Foreign Application Priority DataAttorney-Darby & Darby June 26, 1970 Italy 51726 A/70 [57] ABSTRACT [52]US. Cl. 92/13.3, 92/137,;2/325 The pump comprises two cylinders withpistons actw 51 1111. C1. F01b 31/14, F04b 23 06 med a shaft fittedeccemrcs spending to each piston, between each eccentric and [58] Fieldof Search ..92/l3, 13.3, 3,13.7,

92/86 417/429 539 533 the large end of each connecting rod beinginterposed a disc with an opening which receives said eccentric, saidopening being offcentered with respect to said disc [56] ReferencesCited so that by rotating said disc with respect to said eccen- UNITEDSTATES PATENTS tric the crank radius of the connecting rod and conse-1,328,474 1/1920 Astrom 92/86 X quently the stroke of the correspondingpiston can be 2,136,599 11/1938 Thompson et a1. 92/86 x varied at m2,612,839 10/1952 Denny 92/133 2,957,422 10/1960 Loeber 92/13.7 4Claims, 3 Drawing Figures 54 55 32 5/ 45 155 46 92' 2s .96 CD56 52 .54.9 4o .55 50 VARIABLE STROKE MULTIPLE PUMP The present invention refersto variable stroke multiple pumps.

In many applications it becomes necessary to pump a number of liquids ina preselected constant mutual proportion. In many other applications itis also imperative to pump these liquids simultaneously but in separateflows, especially in the case of reactive liquids, in order to preventthem from mixing and reacting upstream of or within the pump.

The invention provides therefore a pluricylinder pump comprising anumber of variable stroke pumping units, each pumping a separate fluid,the pistons of these units being reciprocated by a common shaft. Themutual pumping proportions can be selected by means permitting to vary,on said common shaft, the crank radius relatively to each piston.Thereby, said proportions, once set, are not affected by the speed ofthe pump shaft.

The means for varying the crank radius comprise, for each individualpiston, an eccentric rigid with said shaft, said eccentric beingrotatable within a matching circular opening, which is provided in adisk and offcentered with respect to the latter. On said disk is mountedthe annularly shaped eye of the large or crankpin end of the connectingrod. The stroke of each piston is varied by rotating the disk around theeccentric till the required crank radius is obtained, and fixing it inposition. Further means are provided to readily vary the relativeposition of each pair of eccentrics from the exterior. Since all pistonsare driven from a common shaft, the proportions at which each liquid ispumped will of course remain constant, independently of the speed of thepump shaft.

The pistons present two sets of packings, one at their top portion, theother at the bottom portion, and thereby they divide their associatedcylinder into an upper and a lower chamber, the upper communicating withthe liquid, the other communicating with the external air through atleast one aperture in the cylinder walls. Thereby the liquid in theupper chamber is prevented from coming into contactwith the lubricatingoil of the pump, as it will be explained later in greater detail.

A possible embodiment of the pump will now be described with reference-to the attached drawings, wherein:

FIG. 1 is a lateral partial sectional view of a pump embodying theinvention,

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1, and

FIG. 3 is an enlarged sectional view of a detail of FIG.

With reference to the drawings, the pump housing also contains thestep-up gearing transmitting the drive from a motor to the pump shaft.The drive shaft 16 is rotatably supported in the housing 10 in twobearings 12 and 14 and its end projecting beyond the housing carries apulley l8 fastened to it by a bolt and a washer 22. A spur gear 24 keyedto shaft 16 meshes with a spur gear 26 ofa much smaller diameter keyedto the pump shaft 28, to form the step-up mechanism transmitting thedrive from the motor to the pump.

Two circular eccentrics 34 and 36 are keyed to the pump shaft 28. Eacheccentric is positioned within a matching circular opening of a disk 38,40 respectively,

the openings being offcentered with respect to said disks. A pin 42 and44 respectively projects laterally from each disk 38, 40, on which areoscillatabiy mounted the annular crankpin ends 55, 57 of connecting rods54, 56 respectively.

The portions of the pump shaft 28 which extend on both sides from theeccentrics 34, 36 to the shaft ends are supported on bushings 46 and 48respectively, which are in turn rotatable in the housing 10 on bearings30 and 32 respectively. Adjacently to the eccentrics, each bushing formsa circular flange 47, 49 respectively. Each flange is provided with aradial slot 50 and 52 respectively, into which engages the pin 42 and 44respectively projecting from the adjacent lateral surfaces of each disk38, 40. Each disk 38, 40 and eye 55, 57 is retained upon its respectiveeccentric 34, 36 by flange 35, 37 provided on each eccentric 34, 36. Aknurled wheel 51 and 53 respectively is keyed to each bushing externallyof housing 10. A graduated plate 94 and 96 is keyed to each terminalportion of shaft 28. By rotating one of the graduated plates 94, 96respectively relatively to its corresponding wheel 51, 53, also the diskassociated with the bushing by the pin 42, 44 is rotated relatively tothe corresponding eccentric, and thereby the crank radius R and thus thestroke of the corresponding piston is varied steplessly. The wheel canbe provided with an index mark, and the graduation on the plates 94, 96may correspond either directly to the stroke of the piston or to thepiston displacement.

The stroke of each piston can be set independently of that of the otherpiston and therefore the proportions of the fluids delivered througheach cylinder can be steplessly varied at will by positioning the wheels51, 53 relatively to the graduated plates 94, 96 and fastening them bytightening the bolts 90, 92 respectively.

The pistons 58 and 60 associated with the connecting rods 54 and 56respectively have two disks 62, 66 and 64, 68 respectively, and operatein two cylinders 70 and 72, respectively. The cylinder 70 is divided bythe disks of piston 58 in an upper chamber 74 extending between thecylinder head and the disk 62, and a lower chamber 76 extending betweensaid disk 62 and the disk 66. As shown in FIG. 2, one of the fluids ispumped from the suction side 78 into the chamber 74 and thence into thedischarge side 80, which is provided in the usual manner with an airchamber 82. The chamber 76 communicates with the exterior through slits97. This chamber serves to prevent any contact between the fluids to bepumped and the lubricating oil of the pump even in case where the pistonpackings become defective. In fact, either the oil which might leakthrough the packing of the lower piston disk or the fluid which mightleak through the packing of the upper disk are discharged through saidslits. Also the piston 60 divides its relating cylinder 72 into an upperchamber 84 and a lower chamber 86. The pumping circuit is identical tothat of the cylinder 70 and is therefore neither described norillustrated. Similarly also the discharge pipe of cylinder chamber 84may be provided with an air chamber 88. The bores of the cylinders mightbe of identical or different size.

I claim:

1. A- two-cylinder pump for pumping two fluids at respective variablerates comprising:

a rotatable pump shaft;

a pair of eccentrics mounted in spaced relationship on the pump shaft;

a pair of disks, each of the disks having an opening formed therein formounting said disk on a respective one of the eccentrics in aselectively variable position;

a pair of piston members, each piston member having an associated pistonrod formed with an eye at the end thereof rotatably mounted on arespective one of the disks;

a flange formed on each of said eccentrics extending over and abutting aside surface of the associated piston rod eye and corresponding disk forretaining each disk and piston rod eye mounted on its associatedeccentric and disk respectively; and

a pair of bushings fitted over respective ends of the pump shaft, eachbushing having a flange formed thereon which extends over and abuts theother side surface of the associated piston rod eye and correspondingdisk for retaining each disk and piston rod eye mounted on itsassociated eccentric and disk respectively, and means for selectivelyindependently varying the relative position of each disk with respect toits associated eccentric including engaging means provided on each saidbushing and eccentric engaging each eccentric to an associated bushingfor rotating said eccentric in response to rotation of said associatedbushing 2. A two-cylinder pump as defined in claim 1 wherein said meansengaging each eccentric to an associated bushing includes a slotprovided in either said eccentric or bushing and a pin member providedin the other of said eccentric or bushing extending into said slot forsliding movement therein.

3. A two cylinder pump as recited in claim 1, wherein each piston membercomprises an upper and lower piston, which upper piston defines an uppercylinder chamber extending from the upper piston to the cylinder headand which lower piston defines a lower cylinder chamber extendingbetween the two pistons.

4. A two cylinder pump as recited in claim 3, wherein each uppercylinder chamber has a fluid inlet and a fluid discharge for passage ofeach pumped fluid and wherein the lower cylinder chamber has at leastone opening formed therein providing fluid communication between theinterior of the lower cylinder chamber and the exterior of the pump sothat any of the pumped fluid which leaks down past the upper piston orany lubricating oil which is normally disposed in the pump casing whichleaks past the lower piston will be discharged through the opening tothe pump exterior.

1. A two-cylinder pump for pumping two fluids at respective variablerates comprising: a rotatable pump shaft; a pair of eccentrics mountedin spaced relationship on the pump shaft; a pair of disks, each of thedisks having an opening formed therein for mounting said disk on areSpective one of the eccentrics in a selectively variable position; apair of piston members, each piston member having an associated pistonrod formed with an eye at the end thereof rotatably mounted on arespective one of the disks; a flange formed on each of said eccentricsextending over and abutting a side surface of the associated piston rodeye and corresponding disk for retaining each disk and piston rod eyemounted on its associated eccentric and disk respectively; and a pair ofbushings fitted over respective ends of the pump shaft, each bushinghaving a flange formed thereon which extends over and abuts the otherside surface of the associated piston rod eye and corresponding disk forretaining each disk and piston rod eye mounted on its associatedeccentric and disk respectively, and means for selectively independentlyvarying the relative position of each disk with respect to itsassociated eccentric including engaging means provided on each saidbushing and eccentric engaging each eccentric to an associated bushingfor rotating said eccentric in response to rotation of said associatedbushing.
 2. A two-cylinder pump as defined in claim 1 wherein said meansengaging each eccentric to an associated bushing includes a slotprovided in either said eccentric or bushing and a pin member providedin the other of said eccentric or bushing extending into said slot forsliding movement therein.
 3. A two cylinder pump as recited in claim 1,wherein each piston member comprises an upper and lower piston, whichupper piston defines an upper cylinder chamber extending from the upperpiston to the cylinder head and which lower piston defines a lowercylinder chamber extending between the two pistons.
 4. A two cylinderpump as recited in claim 3, wherein each upper cylinder chamber has afluid inlet and a fluid discharge for passage of each pumped fluid andwherein the lower cylinder chamber has at least one opening formedtherein providing fluid communication between the interior of the lowercylinder chamber and the exterior of the pump so that any of the pumpedfluid which leaks down past the upper piston or any lubricating oilwhich is normally disposed in the pump casing which leaks past the lowerpiston will be discharged through the opening to the pump exterior.